Extruders used to produce objects made of extrudable materials are well known. Such extruders generally comprise a hopper through which an extrudable material is introduced into the extruder; a heating element to melt the extrudable material if such material is a thermoplastic; and an aperture or die through which the extrudable material is extruded.
There is a need to produce extruded objects having a cross-sectional profile that varies along its length by varying the size and shape of said aperture during the extrusion process. An extruder die having such a variable means for defining an aperture shaping means allows the extrusion, for example, of thermoplastic articles such as baseball bats, bowling pins, water toys and the like.
Means for extruding articles having a cross-sectional profile that varies along its length is also known.
U.S. Pat. No. 2,578,229 teaches a draw plate comprising a series of interlocked jaws defining a polygonal opening and means for adjusting the size of such opening so as to provide varying cross-sections for drawn members such as rods, bars and tubes and the like.
Means for shaping and cutting spherical objects from dough are also disclosed in U.S. Pat. Nos. 4,734,024, 5,153,010 and 5,190,770.
U.S. Pat. No. 4,734,024 relates to an apparatus for shaping a round body consisting of dough and filling. Said apparatus contains a cutter assembly having at least three circumferentially disposed cutter members arranged in sliding contact with each other so as to form a central aperture. Said central aperture is openable for receiving a leading part of a cylindrical body of dough and filling, and closable for shaping the received part into a shaped body substantially polygonal in form and severing it from the remainder of said cylindrical body of dough and filling.
U.S. Pat. No. 5,153,010 teaches an improved apparatus for cutting and shaping a spherical form made of dough with a filling. Said apparatus has a structure capable of accommodating a greater number of shaping members, hence, allowing dough to be a shaped into a form that is more substantially spherical than in U.S. Pat. No. 4,734,024. Said improved apparatus comprises a plurality of identically shaped polygonal members, each of which having a first end pivotally connected to one of a plurality of supports which are disposed equidistantly around a circular opening, and which polygonal members collectively define an aperture. Each of said polygonal members has a tip, first curved side and second curved side. When said polygonal members are in the open position, the first curved side of each of the polygonal members abuts said second curved side of the adjacent polygonal member. When said polygonal members are in the closed position, said tip of each of the polygonal members is disposed at the central point of said circular opening.
Similarly, U.S. Pat. No. 5,190,770 discloses another apparatus for cutting and shaping a spherical body which is particularly adapted to forming spherical articles from dough. The apparatus taught therein discloses a plurality of identically shaped cutting and shaping members, one end of each of the members being pivotally fitted to each of a plurality of fulcrums that are equidistantly disposed on an imaginary circumference formed by connecting said fulcrums, and the opposite end of each of said shaping members being formed into a tip so that said shaping members collectively and radially form and close an opening concentric to the circumference surrounded by said shaping members when each of said shaping members pivots away from and towards the centre of the circumference, respectively, thereby to cut and shape the dough passing through said opening.
Variable closure means more particularly adapted for extruding thermoplastic articles are also known.
U.S. Pat. No. 3,932,090 discloses an apparatus for extruding articles having integral ribs and/or integral rows of spaced apart elements extending transverse to the direction of extrusion by extruding melt flowable material in a first annular extrusion zone while the melt flowable material being extruded in a second annular extrusion zone is periodically interrupted, modulated and/or restricted.
U.S. Pat. No. 4,187,068 teaches an apparatus for extruding an elongated article having a cross-sectional profile which varies along its length comprising a die plate, stationary die block and plurality of die members. Said die members and stationary die block are mounted on said die plate and form together an orifice. A controllable drive means is also provided for to allow said die members to be moved contemporaneously along channels so as to modify the shape and size of said orifice.
It is an object of this invention to provide for a more efficient and simple apparatus for producing elongated articles from extrudable materials, comprising an extruder, first retaining member, second retaining member, sealing means and moveable means for defining an aperture disposed between said first and second retaining members. It is still a further object to provide for a process for extruding an elongated article having a cross-sectional profile that varies along its length by heating a melt flowable material in an extruder, extruding said melt flowable material through a moveable means for defining an aperture, and sealing said moveable means to said extruder. Finally, it is also an object of this invention to provide for an elongated article extruded from a thermoplastic material having a cross-sectional profile that varies along its length.
The moveable means for defining an aperture used in the present invention comprises an iris. The iris allows the shaping of objects that are more substantially spherical in shape than the apparati disclosed in the prior art, particularly U.S. Pat. No. 4,187,068. Furthermore, the cross-sectional profile of the aperture defined by said iris can be modified during the extrusion process with greater ease and speed than the controlling drive means and channels disclosed in U.S. Pat. No. 4,187,068 which in turn allows more efficient extrusion of elongated articles having a cross-sectional profile, and also permits greater variance of the cross-sectional profile of such elongated articles along their length when the same are extruded continuously. The iris used in the present invention also has cost advantages over other variable closure means disclosed in the prior art.